Spawn Rates bug

I have some problem with the spawn rates of mcpe .1.1 build 4 Animals and Hostile mobs not the same as In PC im making a mob grinder that definitly working but not on MCPE 1.1.0.4 im making it the same as in MC PC and try it to MCPE but not working at all. Please Can you make it accurate as MC PC cause some of my build are not working in MCPE only at MC PC